The present invention relates essentially to a preserved or canned aqueous food product or foodstuffs packed under high or deep vacuum, a method of obtaining same, as well as a device for carrying out this process and a container lid or cover and a container adapted to be used for performing the method.
Aqueous foodstuffs or products as meant by or within the scope of the present invention in particular comprise not only products of vegetable origin such for instance as fruits, vegetable, mushrooms but also those of animal origin such as meats and fishes. The expression indeed covers any natural foodstuffs or product likely to be added with water without impairing or damaging the organoleptic qualities thereof.
There are presently known two kinds of processes for preserving such aqueous food products or foodstuffs according to their sensitivity to oxidation.
With products containing substances likely to be spoiled upon being contacted by oxygen, a brining or juicing process is used. The food product and the covering juice or liquid which may for instance be salt water or brine or a golden syrup are introduced into a container or vessel such as for instance; a can or a tin after having undergone a previous treatment to extract or release the gas therefrom. This treatment consists in blanching the food product and heating or warming the juice or brine up to a temperature close to 100.degree. C. Such a process is particularly applicable to green peas packed in cans or jars and is effective to avoid the yellowing of this product and its getting a lucern-like taste. This method however suffers from the following inconveniences:
a dilution in the juice or brine of a part of the nineral salts, vitamins, pigments as well of any kind of molecules providing taste, flavour or tang and scent or smell;
an impairment, adulteration or deterioration of texture qualities caused by longer sterilizing times then those used for the packaging or conditioning of products under vacuum.
With products which are little sensitive to oxidation such for instance as soft maize or corn, a method of preserving under partial vacuum has already been used for many years. This method consists in a preservation of the product under an absolute pressure lower than or equal to 360 mm of mercury column.
According to this known method the product is introduced into a container without any previous blanching and then a few grams of a juice or brine is added before sealing, crimping or seaming the container provided with a closure lid or cover by means of a vacuum sealing, seaming or crimping machine. Thus a food product is obtained which is preserved under an oxygen-containing atmosphere and which is stable since it consists essentially of sugars which are little sensitive to oxidation.
Such a method may however not be used for preserving most of the aqueous food products or foodstuffs since the latter incorporate oxygen-sensitive compounds such as polyunsaturated fatty acids, tannins, vitamins and so on.